Pressure processing a pumpable substance with a flexible membrane

ABSTRACT

An apparatus and method for pressure processing a pumpable substance, such as a pumpable food product or slurry. In one embodiment, the apparatus includes a pressure vessel having an inlet valve toward one end and outlet valve toward the other end. A flexible bladder is coupled between the inlet and outlet valves for receiving the pumpable substance. The pressure vessel can further include a high-pressure inlet port for receiving high-pressure fluid that biases the membrane inwardly to pressure process the pumpable substance. The pumpable substance is then removed from the vessel through the outlet valve.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a divisional of U.S. Patent Application No.09/374,649, filed Aug. 13, 1999, now pending, which application isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to methods and devices for pressureprocessing pumpable substances, such as food or abrasive slurries, usinga flexible membrane.

[0004] 2. Description of the Related Art

[0005] Conventional ultrahigh-pressure fluid systems have been used topressurize pumpable substances, such as foods and slurries. For example,conventional ultrahigh-pressure systems have been used to improve thequality and longevity of food by subjecting the food to pressures inexcess of 10,000 psi. Conventional systems have also been used topressurize abrasive slurries to ultrahigh-pressure levels. The slurriescan then be directed toward a substrate in the form of a liquid jet tocut the substrate or treat the surface of the substrate.

[0006] One conventional system includes a high-pressure cylinder with aslidable piston that divides the cylinder into two regions. The pumpablesubstance is placed in one region while a high-pressure fluid isintroduced into the other region, driving the piston against thepumpable substance at a very high pressure. One potential drawback withthis system is that as the piston may require specially designed sealsto prevent the highpressure fluid from being transported by the pistoninto the pumpable substance region. The seals may require periodicmonitoring and replacement. Accordingly, it may be desirable to use animproved apparatus for pressurizing a pumpable substance while reducingthe likelihood for contact between the pumpable substance and thepressurizing liquid.

BRIEF SUMMARY OF THE INVENTION

[0007] The invention relates to methods and apparatus for pressureprocessing a pumpable substance, such as a food substance. In oneembodiment, the apparatus includes a generally rigid high-pressurevessel having a first opening toward one end, a second opening towardthe other end, and an internal vessel wall between the first and secondends. A flexible membrane is disposed within the vessel and has a firstmembrane opening in fluid communication with the first open end of thevessel and a second membrane opening in fluid communication with thesecond opening of the vessel. At least a portion of the membrane ismovable away from the vessel wall to pressurize a portion of thepumpable substance positioned adjacent to the membrane.

[0008] In one embodiment, the second membrane opening can be positionedbeneath the first membrane opening so that the pumpable substance canexit the membrane through the second opening under the force of gravity.In another embodiment, valves are coupled to the first and secondopenings of the high-pressure vessel. In one aspect of this embodiment,the valves can each include a passage having a first portion with afirst opening and second portion with a second opening. A piston issealably positioned in the passage and axially movable within thepassage between a closed position with the piston blocking fluidcommunication between the first and second openings and an open positionwith the first and second openings being in fluid communication witheach other. The pumpable substance can be pumped into the membranethrough the first opening, pressurized within the membrane by ahigh-pressure fluid disposed between the membrane and an inner wall ofthe vessel, and released from the pressure vessel through the secondopening.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0009]FIG. 1 is a partially schematic, partial cross-sectional sideelevation view of an apparatus having an inlet valve, an outlet valveand a bladder in accordance with an embodiment of the invention.

[0010]FIG. 2 is a detailed partial cross-sectional side elevation viewof an upper portion of the apparatus of FIG. 1 showing the inlet valvein its open position.

[0011]FIG. 3 is a detailed partial cross-sectional side elevation viewof the upper portion of the apparatus of FIG. 1 showing the inlet valvein its closed position.

[0012]FIG. 4 is a detailed partial cross-sectional side elevation viewof the lower portion of the apparatus of FIG. 1 showing the outlet valvein its closed position.

[0013]FIG. 5 is a partial cross-sectional side elevation view of theapparatus shown in FIG. 1 having an inlet valve in accordance withanother embodiment of the invention.

[0014]FIG. 6 is a partial cross-sectional top view of the inlet valve ofFIG. 5 shown in its open position.

[0015]FIG. 7 is a partial cross-sectional top view of the inlet valve ofFIG. 5 shown in its closed position.

DETAILED DESCRIPTION OF THE INVENTION

[0016] In general, conventional devices for pressure processing pumpablesubstances have been directed to high-pressure cylinders having aninternal piston and/or having an inlet and outlet for the pumpablesubstance at one end of the cylinder and an inlet and outlet for thehigh-pressure fluid at the opposite end of the cylinder. By contrast,one aspect of the present invention includes a high-pressure cylinderhaving a flexible bladder with an entrance opening for the pumpablesubstance at one end of the bladder and an exit opening for the pumpablesubstance at the opposite end of the bladder. Accordingly, in oneembodiment, the pumpable substance can be introduced through an inletport at one end of the cylinder and removed from an outlet port at theopposite end of the cylinder, reducing the likelihood for contaminationof the outlet port with unpressurized pumpable substance. The apparatuscan also take advantage of gravitational forces to more completelyremove the pumpable substance from the pressure vessel. Furthermore, byseparating the inlet and outlet ports, each port can be larger,increasing the rate at which the pumpable substance can be moved intoand out of the bladder, and increasing the size of pumpable substanceconstituents that can pass into and out of the bladder.

[0017] An apparatus 10 for pressure processing a pumpable substance inaccordance with an embodiment of the invention is shown in FIG. 1. Theapparatus 10 includes a pressure vessel 12 that receives the pumpablesubstance from a pumpable substance source 30 and pressurizes thepumpable substance with fluid supplied by a highpressure fluid source41. The pressure vessel 12 can include an open-ended cylinder 13surrounded by a protective cylindrical shield 14. Two valve assemblies20, shown as an inlet valve assembly 20 a and an outlet valve assembly20 b, cap opposite ends of the cylinder 13, and are clamped against thecylinder 13 with a yoke 11. A flexible bladder 50 is coupled between thevalve assemblies 20. The pumpable substance is pumped into the bladder50 through the inlet valve assembly 20 a, pressurized by high-pressurefluid entering the cylinder 13 from the high-pressure fluid source 41,and pumped through the outlet valve assembly 20b to a receptacle 80, aswill be discussed in greater detail below.

[0018] In one embodiment, the pressure vessel 12 can include a modelnumber 012122 assembly available from Flow International Corporation ofKent, Washington that includes the cylinder 13, the yoke 11 and theshield 14, configured to withstand an internal vessel pressure of atleast 100,000 psi. In other embodiments, the pressure vessel 12 caninclude other cylinders 13 and peripheral components configured towithstand an internal pressure of 100,000 psi or another suitablepressure, depending upon the selected pumpable substance and treatment.Such vessels and components are available from ABB Pressure Systems ofVasteras, Sweden, Autoclave Engineering of Erie, Pa., or EngineeredPressure Systems of Andover, Mass.

[0019] The pressure vessel 12 can include a liner 15 adjacent an innersurface of the cylinder 13. The liner can be formed from stainless steelor other suitable materials that can withstand the high internalpressures within the cylinder 13. In one embodiment, the liner 15 can beattached to the cylinder 13 by first heating the cylinder 13 so that itexpands, then placing the cylinder 13 around the liner 15, and thencooling the cylinder 13 so that it shrinks tightly around the liner 15.If the liner 15 later becomes worn or damaged, it can be removed fromthe cylinder 13 and replaced with a similar liner. An advantage of thisarrangement is that cracks that might result from the high pressurewithin the pressure vessel 12 will tend to form in the liner 15 ratherthan in the cylinder 13, and it may be easier and less expensive toreplace the liner 15 than the cylinder 13.

[0020]FIG. 2 is an enlarged cross-sectional side elevation view of theupper portion of the apparatus 10 shown in FIG. 1. As shown in FIG. 2,the inlet valve assembly 20 a fits partially within the cylinder 13 andincludes a flow channel 31 having a radial portion 32 in fluidcommunication with an axial portion 33. Both the radial portion 32 andthe axial portion 33 can be strengthened or reinforced, for example, bypassing through these portions a die having a slightly oversizeddiameter, or by using other known strengthening techniques. An inletport 27 a at one end of the radial portion 32 is coupled to the pumpablesubstance source 30 (FIG. 1). A bladder port 34 at the opposite end ofthe axial portion 33 is coupled to the bladder 50. An inlet sealingpiston 22 a moves axially upwardly and downwardly within the axialportion 33 between an open position (shown in FIG. 2) in which thepumpable substance can pass into the bladder 50 and a closed position(discussed in greater detail below with reference to FIG. 3) in whichthe pumpable substance is sealed within the bladder 50.

[0021] When the inlet valve assembly 20 a is in its open position, theinlet sealing piston 22 a is retracted upwardly into a sealing block 23.An upper piston seal 70 a, disposed annularly about the inlet sealingpiston 22 a, seals the interface between the inlet sealing piston 22 aand the axial portion 33 of the flow channel 31 to at least restrict thepumpable substance from passing upwardly along the inlet sealing piston22 a. A lower fluid gap 38 a extends annularly about the inlet sealingpiston 22 a, just above the upper piston seal 70 a, for collecting andremoving pumpable substance that might escape past the upper piston seal70 a. Purging fluid can be pumped through an upper inlet port 28 a andinto the lower fluid gap 38 a, where it can entrain pumpable substancethat might be present in the lower fluid gap 38 a. The purging fluid andentrained pumpable substance can then be removed through an upper exitport 29 a. In one embodiment, the purging fluid can include water, andin other embodiments the purging fluid can include iodine or othersubstances that sanitize the surfaces in contact with the purging fluid.

[0022] The inlet valve assembly 20 a further includes a lower seal 70 bbeneath the upper seal 70 a. When the inlet sealing piston 22 a is inits open position (as shown in FIG. 2), the lower seal 70 b is coveredwith a sleeve 74 that is biased upwardly by a sleeve spring 75. Thesleeve 74 protects the lower seal 70 b from contact with the pumpablesubstance. The lower seal 70 b is exposed and seals against the inletsealing piston 22 a when the inlet sealing piston 22 a is moved to itsclosed position, as will be discussed in greater detail below.

[0023] The inlet sealing piston 22 a is driven from its open position toits closed position by a driver piston 21 that moves axially within thesealing block 23. Accordingly, the sealing block 23 includes a driverfluid port 25 that supplies pressurized fluid to the driver piston 21 tomove the driver piston and the inlet sealing piston 22 a together in adownward direction. The sealing block 23 itself can slide laterallyalong a block rail 24 to secure the inlet sealing piston 22 in theclosed position. Accordingly, the sealing block 23 can include anactuator 26 that moves the sealing block 23 laterally back and forthalong the block rail 24.

[0024] In operation, the inlet sealing piston 22 a moves downwardly fromits open position to its closed position under the force of the driverpiston 21. As the inlet sealing piston 22 a moves downwardly, it engagesthe sleeve 74, forcing the sleeve downwardly against the resistanceprovided by the sleeve spring 75. At this point, both the upper seal 70a and the lower seal 70 b seal against the inlet sealing piston 22 a andthe inlet sealing piston 22 a blocks communication between the radialportion 32 and the axial portion 33 of the flow channel 31. The inletsealing piston 22 a continues to move in a downward direction until anend cap 35 at the upper end of the inlet sealing piston 22 a is alignedwith a cap engaging surface 36 of the sealing block 23. The sealingblock 23 then slides laterally as indicated by arrow A along the blockrail 24 until the end cap 35 engages the cap retaining surface 36. Theinlet sealing piston 22 a is accordingly secured in its closed position.

[0025] To open the valve 20 a, the sealing block 23 is moved laterallyas indicated by arrow B until the driver piston 21 is axially alignedwith the inlet sealing piston 22 a. The sleeve spring 75 then moves thesleeve 74 upwardly, and the sleeve 74 together with pressure from withinthe bladder 50 drive the inlet sealing piston 22 a upwardly to its openposition.

[0026]FIG. 3 is a cross-sectional side elevation view of the inlet valve20 a of FIG. 2 shown in the closed position. The inlet sealing piston 22a has moved downwardly in the axial portion 33 of the flow channel 31and the sealing block 23 has moved laterally so that the cap engagingsurface 36 engages the end cap 35 to prevent the inlet sealing piston 22a from moving in an upward direction. The inlet sealing piston 22 a hasmoved the sleeve 74 downwardly so that the lower piston seal 70 bengages the inlet sealing piston 22 a. Accordingly, the lower fluid gap38 a, now positioned just above the lower piston seal 70 b, is alignedwith a lower inlet port 28 b and a lower exit port 29b to removepumpable substance from the lower fluid gap 38 a in a manner generallysimilar to that discussed above with reference to FIG. 2. An upper fluidgap 38 b is aligned with the upper inlet port 28 a and the upper exitport 29 a to operate in a manner similar to that discussed above withreference to FIG. 2. Accordingly, the inlet valve 20 a can prevent thepumpable substance from escaping upwardly past the inlet sealing piston22 a when the inlet valve 20 a is in its closed position and the bladder50 is under pressure.

[0027] As shown in FIG. 3, the bladder 50 is attached to the sleeve 74to receive the pumpable substance through the inlet valve 20a. In oneembodiment, the bladder 50 includes an elongated tube having an upperopening 54. The bladder 50 can be formed from rubber, neoprene or anyflexible, generally nonporous material. In one embodiment, the bladder50 can include a medical-grade rubber suitable for use with foodproducts. In another embodiment, the bladder 50 can include anabrasion-resistant rubber or other abrasion resistant material for usewith abrasive slurries. In still another embodiment, the bladder 50 caninclude a laminate of multiple plies bonded together with an adhesive,such as a rubber cement. One advantage of this embodiment is that thebladder 50 can separate the pumpable substance from the high-pressurefluid even if one or more of the plies has a pin hole or other puncture.Another advantage is that the multiple plies can thicken the bladder 50and provide thermal insulation between the pumpable substance and thehighpressure fluid. Accordingly, hot or cold pumpable substances can bepressure processed in the pressure vessel 12 with a reduced transfer ofheat to or from the pumpable substance.

[0028] A bladder fitting 51 extends through the upper opening 54 of thebladder 50 and is attached to the bladder 50 with a band 53 oralternatively, with a food-grade adhesive that discourages microorganismgrowth, or another suitable securing device. The bladder fitting 51 isthen coupled to the sleeve 74 with a removable coupling 52, such as areavailable from Tri-Clover, Inc., of Kenosha, Wis. In one embodiment, thebladder fitting 51 can be sized to take up a substantial volume withinthe cylinder 13, thereby reducing the volume of high-pressure fluidrequired to pressurize the bladder 50 and reducing the time required tomove the high-pressure fluid into and out of the cylinder 13.

[0029]FIG. 4 is a cross-sectional side elevation view of the lowerportion of the apparatus 10 shown in FIGS. 1-3. As shown in FIG. 4, thebladder 50 includes a lower opening 55 attached to a bladder fitting 51which is in turn coupled to a sleeve 74 of the outlet valve assembly 20b. In one embodiment, the bladder 50 can be stiffer near the loweropening 55 than near the upper opening 54 (FIG. 3) to prevent thebladder 50 from collapsing on itself near the lower opening 55 when thepumpable substance is removed. In one aspect of this embodiment, thestiffness of the bladder 50 can decrease in a generally uniform mannerin an upward direction extending away from the outlet valve assembly 20b. In another aspect of this embodiment, the bladder 50 can be madestiffer near the lower opening 55 by increasing the number of plies thatform the bladder 50 in this region.

[0030] The outlet valve assembly 20 b includes an outlet sealing piston22 b, a driver piston 21 and a sealing block 23, all of which operate ingenerally the same manner as was discussed above with reference to theinlet valve assembly 20 a shown in FIGS. 2 and 3. Accordingly, theoutlet valve assembly 20 b is closed (as shown in FIG. 4) while thepumpable substance is pressurized, and is opened to allow thepressurized pumpable substance to pass out of the bladder 50.

[0031] The outlet valve assembly 20 b includes a high-pressure port 40coupled to the high-pressure fluid source 41 (FIG. 1). The high-pressurefluid enters the pressure vessel 12 through the high-pressure port 40 atpressures up to and exceeding 100,000 psi, fills the region betweencylinder 13 and the bladder 50, and pressurizes the contents of thebladder 50. In one embodiment, the high-pressure fluid can be water.Alternatively, the high-pressure fluid can be sterile citric acid oranother sterile solution. In a further aspect of this embodiment, thehigh-pressure fluid can be selected to include water at an elevatedtemperature, for example, about 100° F. At such elevated temperatures,the ductility of the metal forming the cylinder 13 can be increased, asdetermined using a Charpy test or other ductility tests.

[0032] After pressurization, the pressurized pumpable substance can beremoved through the outlet valve 20 b by moving the outlet valve 20 b toits open position and allowing the pumpable substance to pass through apumpable substance exit port 27 b to the receptacle 80 (FIG. 1). In oneembodiment, the pumpable substance can exit the bladder 50 solely underthe force of gravity. In one aspect of this embodiment, the inlet valve20 a is opened to a sterile environment at atmospheric pressure to allowthe pumpable substance to descend from the bladder 50 under the force ofgravity without introducing contaminants to the bladder 50. In anotherembodiment, the pumpable substance can be squeezed from the bladder 50by filling the pressure vessel 12 with a fluid at a relatively lowpressure. In one aspect of this embodiment (best seen in FIG. 3), thepressure vessel 12 can include a low pressure valve 60 for transportingthe low pressure fluid to and from the cylinder 13.

[0033] The low pressure valve 60 (FIG. 3) can include a fluid passage 62having a fluid port 61 at one end coupled to a source of the lowpressure fluid (not shown). At the opposite end of the fluid passage 62is a movable sealing ring 66 that can be moved between an open position(shown in FIG. 3) that allows fluid communication between fluid passage62 and the interior of the cylinder 13, and a closed position thatprevents such fluid communication. In one embodiment, the sealing ring66 is biased upwardly toward its closed position with a sealing ringspring 67. The sealing ring 66 can be moved downwardly against the forceof the sealing ring spring 67 to its open position by an actuatingpiston 65. The actuating piston 65 can be positioned in a gas passage 64and can move downwardly within the gas passage 64 when gas is suppliedthrough a gas port 63. To close the fluid passage 62, the pressure atthe gas port 63 is reduced, allowing the sealing ring spring 67 to movethe sealing ring 66 and the actuating piston 65 upwardly until thesealing ring seals against the inlet valve assembly 20 a and closes thefluid passage 62.

[0034] In one embodiment, the fluid passage 62 is one of three fluidpassages 62 coupled to the fluid port 61 and spaced 120° apart from eachother around the sleeve 74. Similarly, the gas passage 64 can be one ofthree gas passages 64 coupled to the gas port 63 and spaced 120° apartfrom each other around the sleeve 74. In other embodiments, the lowpressure valve 60 can include more or fewer fluid passages 62 and gaspassages 64. An advantage of having a plurality of gas passages 64 isthat they more evenly distribute the force applied to the sealing ring66, reducing the likelihood that the sealing ring 66 will become cockedor tilted as it moves up and down. An advantage of having a plurality offluid passages 62 is that the low pressure fluid can be more quickly anduniformly transported into and out of the cylinder 13. In anotherembodiment, the outlet valve 20 b (FIG. 4) can also include a lowpressure valve generally similar to the low pressure valve 60 discussedabove. An advantage of having two low pressure valves 60 is that the lowpressure fluid can be even more quickly transported into and out of thecylinder 13. A further advantage is that the inlet and outlet valves 20a, 20 b can be interchangeable.

[0035] Operation of an embodiment of the apparatus 10 is best understoodwith reference to FIG. 1. Initially, the outlet valve assembly 20 b isclosed by moving the outlet sealing piston 22 b to its upper position(shown in FIG. 1) and the inlet valve assembly 20 a is opened by movingthe inlet sealing piston 22 a to its upper position (shown in FIG. 1).The pumpable substance is pumped through the inlet valve assembly 20 aand into the bladder 50. The inlet valve assembly 20 a is then closed bymoving the inlet sealing piston 22 a downwardly and high-pressure fluidis pumped through the high-pressure port 40 of the outlet valve assembly20 b. The high-pressure fluid fills the space between the bladder 50 andthe liner 15 and biases the bladder 50 inwardly to pressurize thepumpable substance within the bladder 50. The pumpable substance is thenpressurized for a selected period of time.

[0036] Turning now to FIG. 3, the low pressure valve 60 is opened byforcing gas through the gas passage 64 to move the actuating piston 65against the sealing ring 66. As the sealing ring 66 moves away from thefluid passage 62, high-pressure fluid escapes through the fluid passage62 and out through the fluid port 61. The outlet valve 20 b (FIG. 1) isthen opened and fluid is supplied at low pressure through the lowpressure valve 60 to collapse the bladder 50 and force the pressurizedpumpable substance out through the outlet valve 20 b. Once the bladder50 has collapsed, the apparatus 10 is ready to pressure process a newbatch of pumpable substance. After a selected number of pressure cycles,the bladder 50 can be cleaned, for example, by passing through thebladder (in succession) a rinse solution, a caustic solution, hot water,a chemical sterilizer and citric acid.

[0037] An advantage of an embodiment of the apparatus 10 shown in FIGS.1-4 is that the bladder 50 can eliminate contact between the pumpablesubstance and the high-pressure fluid. Accordingly, the likelihood thatthat pumpable substance will be contaminated with high-pressure fluid(and vice versa) is substantially reduced. A further advantage is thatthe inlet valve 20 a is separated by a substantial distance from theoutlet valve 20 b, reducing the likelihood of contaminating thepressurized pumpable substance with unpressurized pumpable substance.Furthermore, by positioning the outlet valve 20 b beneath the inletvalve 20 a, the apparatus 10 can take advantage of gravity to remove thepressurized pumpable substance from the vessel 12. Accordingly, agreater portion of the pumpable substance can be removed from the vessel12 after pressurization.

[0038] Yet another feature of the apparatus 10 is that the flow passages31 through the valves 20 can have relatively large cross-sectionalareas. This is advantageous because it allows the pumpable substance toenter and exit the vessel 13 more quickly. It also allows pumpablesubstances having chunks or large suspended particles to be more easilydirected into and out of the vessel 13. For example, when the apparatus10 is used to pressure process chunks of fruit, such as pineapples, theflow passages 31 can have diameters of about one inch. In otherembodiments, the flow passages can have other diameters to accommodatechunks of pumpable substance having other dimensions.

[0039] Still another advantage is that the movable sleeve 74 can reducethe likelihood of exposing at least one of the piston seals 70 b to thepumpable substance. Accordingly, the pumpable substance is less likelyto become trapped in the piston seal 70 b. Yet another advantage is thatthe flow of purging fluid alongside the pistons 22 can further reducethe likelihood of pumpable substance escaping from the vessel 12 whenthe vessel 12 is under pressure.

[0040] In the embodiment discussed above with reference to FIGS. 1-4,the pumpable substance is placed within the bladder 50 and thehigh-pressure fluid is disposed between the bladder 50 and the innerwalls of the cylinder 13. In another embodiment, the pumpable substancecan be positioned between the bladder 50 and the inner walls of thecylinder 13 while the high-pressure fluid is disposed within the bladder50. An advantage of placing the pumpable substance in the bladder 50 isthat it may be easier to remove the pumpable substance from within thebladder 50 than from between the bladder 50 and the walls of thecylinder 13.

[0041]FIG. 5 is a cross-sectional side elevation view of the upperportion of the apparatus 10 shown in FIG. 1 having an inlet valve 120 ain accordance with another embodiment of the invention. The inlet valve120 a includes a low pressure valve 160 generally similar in appearanceand operation to the low pressure valve 60 discussed above withreference to FIG. 3. The inlet valve assembly 120 a further includes aflow channel 131 having an axial portion 133 connected to a radialportion 132. One end of the axial portion 133 is closed with a plug 139,and the other end is coupled to the bladder 50. As will be discussed ingreater detail below, fluid communication between the axial portion 133and the radial portion 132 can be opened or closed by moving a pistonwithin the radial portion 132.

[0042]FIG. 6 is a top, partial cross-sectional view of the inlet valve120 a shown in FIG. 5. As shown in FIG. 6, the inlet valve 120 aincludes a sealing piston 122 that moves laterally within the radialportion 132 of the flow channel 131. When the sealing piston 122 is inits leftmost position (shown in FIG. 6) the pumpable substance can passfrom the radial portion 132 of the flow channel 131 to the axial portion133 and into the bladder 50 (FIG. 5). When the sealing piston 122 is inits rightmost position (discussed in greater detail below with referenceto FIG. 7), the sealing piston 122 prevents fluid communication betweenradial portion 132 and the axial portion 133.

[0043] The sealing piston 122 is sealed within the radial portion 132with two 10 piston seal assemblies 170, shown as a left piston sealassembly 170 a and a right piston seal assembly 170 b. The right pistonseal assembly 170 b is covered with a sleeve 174 when the inlet valve isin its open position (as shown in FIG. 6). The sleeve 174 is biasedtoward the covered position by a sleeve spring 175 when the inlet valve120 a is in the open position, in a manner generally similar to thatdiscussed above with reference to the sleeve 74 shown in FIG. 2. Thesleeve 174 includes an inlet port 127 a coupled to the pumpablesubstance source 30 (FIG. 1) with a flexible conduit 126. Accordingly,the conduit 126 can maintain the connection between the pumpablesubstance source 30 and the inlet port 127 a as the sleeve 174 moveslaterally.

[0044] The seal assemblies 170 can include a seal 171 that extendsbetween the sealing piston 122 and the walls of the radial portion 132of the flow channel 131. The seal assemblies 170 can also include anO-ring 172, an anti-extrusion ring 173 to prevent the seal 171 fromextruding outwardly away from the radial portion 132, and a backup ring176 to support the seal 171 and the anti-extrusion ring 173. This sealassembly arrangement, shown in detail in FIG. 6, can also be used inconjunction with the seals 70 a, 70 b shown in FIGS. 1-4.

[0045] A driver piston 121 connected to one end of the sealing piston122 drives the sealing piston 122 laterally within the radial portion132. The driver piston 121 moves within a driver cylinder 123 which caninclude two driver fluid ports 125 (shown as a left port 125 a and aright port 125 b). When pressurized fluid is supplied to the right port125 b,the driver piston 121 and the sealing piston 122 move to the lefttoward the open position. When pressurized fluid is supplied to the leftport 125 a, the driver piston 121 and the sealing piston 122 move to theright toward the closed position.

[0046]FIG. 7 is a top, partial cross-sectional view of the inlet valveassembly 120 a shown in FIG. 6 with the sealing piston 122 and thedriver piston 121 moved to the closed position. As shown in FIG. 7, thesealing piston 122, when in the closed position, prevents fluidcommunication between the radial portion 132 and the axial portion 133of the flow channel 131. Accordingly, the sealing piston 122 can preventpumpable substance from escaping from the cylinder 13 when the cylinderis pressurized.

[0047] When the sealing piston 122 is in the closed position, it engagesthe sleeve 174 and moves the sleeve 174 to the right (as seen in FIG. 7)until the sealing piston 122 seals against the right seal assembly 170b.Fluid gaps 138 (shown as a left fluid gap 138 a and a right fluid gap138 b) adjacent the sealing piston 122 receive purging fluid from inletports 128 (shown as a left inlet port 128 a and a right inlet port 128b) to purge the region adjacent the seals 170. The purging fluid, withpumpable substance entrained, can be removed through exit ports 129 aand 129 b in a manner generally similar to that discussed above withreference to the fluid gaps 38 shown in FIGS. 2 and 3.

[0048] From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. For example, the liner 15 can bedisposed in a high-pressure vessels that include means other than thebladder 50 for pressurizing the pumpable substance. Accordingly, theinvention is not limited except as by the appended claims.

1. A method for pressure processing a pumpable substance, comprising:introducing the pumpable substance through a first opening of amembrane; pressurizing the pumpable substance by disposing ahigh-pressure fluid between the membrane and a wall of a pressure vesselspaced apart from the membrane; and removing the pumpable substancethrough a second opening of the membrane spaced apart from the firstopening of the membrane.
 2. The method of claim 1 wherein the firstopening of the membrane is positioned above the second opening of themembrane, further comprising moving the pumpable substance in an atleast partially downward direction from the first opening of themembrane to the second opening of the membrane.
 3. The method of claim1, further comprising selecting the pumpable substance from a food or anabrasive slurry.
 4. The method of claim 1, further comprising selectingthe high-pressure fluid to include water.
 5. The method of claim 1,further comprising pressurizing the high-pressure fluid to a pressure ofat least approximately 100,000 psi.
 6. The method of claim 1, furthercomprising selecting a temperature of the high-pressure fluid to beapproximately 100° F.
 7. The method of claim 1, further comprisingadjusting a temperature of the high-pressure fluid from a firsttemperature to a second temperature to raise a Charpy characteristic ofthe vessel from a first value to a second value.
 8. The method of claim1 wherein pressurizing the pumpable substance includes flexing themembrane away from the wall of the pressure vessel.
 9. The method ofclaim 1 wherein pressurizing the pumpable substance includes introducingthe pressurizing fluid through an opening in the wall of the pressurevessel.
 10. The method of claim 1 wherein removing the pumpablesubstance includes disposing the high-pressure fluid between themembrane and the vessel wall while the second opening of the membrane isin fluid communication with a region exterior to the vessel.
 11. Themethod of claim 1, further comprising disposing a liner within thevessel between the vessel wall and the membrane.
 12. The method of claim11, further comprising attaching the liner to the vessel wall.
 13. Themethod of claim 11 wherein the liner is a first liner, furthercomprising removing the first liner and replacing the first liner with asecond liner.
 14. The method of claim 11, further comprising selecting amaterial of the liner to include stainless steel.
 15. The method ofclaim 1, further comprising selecting the membrane to have a generallytubular shape with the first opening toward one end and the secondopening toward an opposite end.
 16. The method of claim 15, furthercomprising controlling a stiffness of the membrane to have a lowerstiffness at a first region near the first opening than at a secondregion between the first and second openings.
 17. A method for pressureprocessing a pumpable substance, comprising: introducing one of thepumpable substance and a pressurizing fluid through a first opening of amembrane; pressurizing the pumpable substance by disposing the other ofthe pumpable substance and the pressurizing fluid between the membraneand a wall of a pressure vessel spaced apart from the membrane; andremoving the pumpable substance through a second opening of the membranespaced apart from the first opening of the membrane.
 18. The method ofclaim 17 wherein introducing one of the pumpable substance and thepressurizing fluid includes selecting the pumpable substance to be afood and introducing the food through the first opening of the membrane.19. The method of claim 17 wherein pressurizing the pumpable substanceincludes disposing the pressurizing fluid between the membrane and thewall of the pressure vessel and biasing the membrane inwardly away fromthe wall of the pressure vessel.
 20. The method of claim 17 whereinintroducing the pumpable substance includes passing the pumpablesubstance into the vessel through a first opening of the vessel andremoving the pumpable substance includes passing the pumpable substanceout of the vessel through a second opening of the vessel spaced apartfrom the first opening of the vessel.
 21. A method for regulating a flowof a pumpable substance into or out of a high-pressure vessel, thevessel having an opening and a valve body in fluid communication withthe opening, the method comprising: moving a piston to a first positionwithin a passage of the valve body to block the flow of pumpablesubstance from a first portion of the passage to a second portion of thepassage while the piston remains sealably engaged with a wall of thepassage; and moving the piston to a second position within the passageof the valve body to permit the flow of pumpable substance from thefirst portion of the passage to the second portion of the passage whilethe piston remains sealably engaged with the wall of the passage. 22.The method of claim 21, further comprising supplying a purging fluid toa region of the passage adjacent to the piston.
 23. The method of claim21 wherein moving the piston includes applying fluid pressure toward oneend of the piston to drive the piston axially within the passage. 24.The method of claim 21 wherein the passage is a valve passage and movingthe piston includes: sliding an actuator within an actuator passagewhile the actuator passage is aligned with the valve passage; engagingthe piston with the actuator to move the piston; separating the actuatorfrom the piston; and axially offsetting the actuator passage from thevalve passage to seal the passages from fluid communication with eachother.
 25. The method of claim 24 wherein moving the piston to the firstposition includes engaging a seal shield with the piston and moving theseal shield axially within the passage to expose a piston seal, furthercomprising engaging the piston seal with the piston.
 26. The method ofclaim 25, further comprising biasing the seal shield toward the piston.27. A method for regulating a flow of a fluid into or out of a pressurevessel, comprising: applying pressure to a first passageway with adriver fluid to move a piston within the first passageway; and engagingthe piston with a sealing member to move the sealing member away from asecond passageway and permit fluid communication between the secondpassageway and the pressure vessel.
 28. The method of claim 27, furthercomprising biasing the sealing member toward the second passageway witha biasing member.
 29. The method of claim 27, further comprisingreducing pressure applied to the first passageway to seal the sealingmember against the second passageway and at least restrict fluidcommunication between the second fluid passageway and the pressurevessel.
 30. The method of claim 27 wherein applying pressure to thefirst passageway includes applying gas pressure to the first passageway.31. The method of claim 27 wherein permitting fluid communicationbetween the second passageway and the pressure vessel includespermitting liquid to flow between the second passageway and the pressurevessel.
 32. A method for replacing a liner of a high-pressure vessel,comprising: removing from the high-pressure vessel a first liner havingan external surface adjacent an interior surface of the high-pressurevessel; disposing a second liner within the high-pressure vessel suchthat an external surface of the second liner is adjacent the interiorsurface of the high-pressure vessel and an internal surface of thesecond liner is spaced apart from the external surface; and sealablyengaging the external wall of the second liner with the interior wall ofthe high-pressure vessel.
 33. The method of claim 32 wherein sealablyengaging the external wall includes expanding the high-pressure vesselbefore disposing the second liner and contracting the high-pressurevessel around the external wall of the second liner after disposing thesecond liner within the high-pressure vessel.
 34. The method of claim 33wherein expanding the high-pressure vessel includes heating thehigh-pressure vessel and contracting the high-pressure vessel includescooling the high-pressure vessel.
 35. The method of claim 32, furthercomprising selecting at least one of the first and second liners toinclude stainless steel.